A Formal Solution to Reichenbach's Reference Class Problem

Abstract

Following Reichenbach, it is widely held that in making a direct inference, one should base one's conclusion on a relevant frequency statement concerning the most specific reference class for which one is able to make a warranted and relatively precise-valued frequency judgment. In cases where one has accurate and precise-valued frequency information for two relevant reference classes, R₁ and R₂, and one lacks accurate and precise-valued frequency information concerning their intersection, R₁∩R₂, it is widely held, following Reichenbach, that no inference may be drawn. In contradiction to Reichenbach and the common wisdom, I argue for the view that it is often possible to draw a reasonable informative conclusion in such circumstances. As a basis for drawing such a conclusion, I show that one is generally in a position to formulate a reasonable direct inference for a reference class that is more specific than either of R₁ and R₂.